JP7036383B2 - Soil purification method - Google Patents

Description

The present invention relates to a soil purification method for purifying underground soil.

In order to purify contaminated soil, there is a method of injecting water into the soil to purify the pollutants in the soil (see, for example, Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 2006-346567 Japanese Unexamined Patent Publication No. 7-82730 Japanese Patent No. 5248423

In Patent Document 1, a pulsed high-pressure gas is injected into the contaminated soil via a tubular body to rearrange the soil particles of the contaminated soil, so that a uniform void for flowing a purifying solution into the contaminated soil. The method of forming is disclosed.

Patent Document 2 discloses a method for purifying contaminated soil by injecting water into contaminated soil from a water injection hole and pumping groundwater from a pumping hole to remove contaminated substances from the contaminated soil.

Further, in Patent Document 3, a plurality of injection wells and pumping wells are excavated in a grid pattern in the contaminated soil layer, water is injected into the contaminated soil layer from the injection wells, and the contaminated substances contained in the groundwater pumped from the pumping wells are introduced. Methods of degradation by microorganisms are disclosed.

By the way, when an injection liquid is injected into a water permeable layer having poor water permeability to purify contaminants, the injection liquid is generally difficult to spread in terms of surface.
For this reason, it is difficult to uniformly distribute the injectate, and it is difficult to remove the pollutants at the site where the amount of the injectate applied per unit volume of the soil is small, and it takes time to remove the pollutants.

In the method of injecting a pulsed high-pressure gas into the contaminated soil using a tubular body to form a void for flowing a purifying agent into the contaminated soil as in Patent Document 1, a void is formed only around the tubular body. Cannot be formed. Therefore, in order to form a water path from the injection well to the pumping well through the contaminated soil, a tubular body is inserted into the hole formed by boring the injection well or multiple points around the pumping well. High pressure gas must be injected into the contaminated soil. Therefore, when purifying contaminated soil over a wide area, boring work and high-pressure gas injection work become extremely complicated.

Further, as in Patent Document 3, by arranging a plurality of injection wells and pumping wells in a grid pattern, it is possible to distribute the water to be injected uniformly to some extent. The work of excavating in a grid pattern becomes extremely complicated.

In view of the above facts, an object of the present invention is to provide a soil purification method capable of efficiently purifying soil even in a permeable layer in which the injection liquid spreads and is difficult to spread.

The method for purifying soil according to claim 1 is to pressurize the permeable layer between the upper and lower permeable layers to increase the internal pressure of the permeable layer and push up the permeable layer above the permeable layer. The first step of forming a liquid passage between the water permeable layer and the upper impervious layer, and after forming the liquid passage, an injection liquid is injected from one side of the water permeable layer to make the water permeable. It has a second step of pumping the injection liquid from the other side of the layer to purify the permeable layer.

In the soil purification method according to claim 1, the permeable layer is pressurized and the impervious layer above the impermeable layer is pushed up to forcibly generate a blister on the impermeable layer above, and the permeable layer and above the impermeable layer. A liquid passage through which the injection liquid passes can be formed at the boundary with the impermeable layer.

When the purifying liquid is injected into the permeable layer in this state, the injected liquid flows at the boundary between the permeable layer and the impervious layer above it, and the injected liquid is in a state where it easily spreads in a surface manner. Then, the spread injection liquid permeates the permeable layer, which enables efficient purification of pollutants in a short time.

According to the second aspect of the present invention, in the soil purification method according to the first aspect, the impermeable wall installation step of installing the impermeable wall surrounding the permeation layer to be purified is performed before the first step. Have.

By surrounding the water-permeable layer with a water-impervious wall before the first step, the water-permeable layer can be efficiently pressurized. As a result, it is possible to efficiently cause blistering on the upper impermeable layer.

The invention according to claim 3 is the method for purifying soil according to claim 1 or 2, wherein in the second step, before injecting the injection liquid into the permeable layer, inside the liquid passage. The coarse-grained material is filled so that the injection liquid can pass through.

When a blister is generated in the upper impervious layer, a liquid passage through which the liquid passes between the impervious layer and the upper impervious layer, in other words, a gap is formed.
By filling the inside of the liquid passage with a coarse-grained material so that the injected liquid can pass through, the coarse-grained material supports the load of the upper ground and the liquid passage is suppressed from being crushed. Therefore, even after the pressurization to the permeable layer is stopped, the shape of the liquid passage can be maintained and the injected liquid can pass through.

According to the soil purification method of the present invention, soil purification can be efficiently performed.

It is a front sectional view which shows the pollutant decomposition purification system which concerns on embodiment of this invention. It is a top view which shows the pollutant decomposition purification system which concerns on embodiment of this invention. It is a front sectional view which shows the pollutant decomposition purification system which performs a pressurizing process. It is a front sectional view which shows the pollutant decomposition purification system which performs a flushing process. It is a front sectional view which shows the pollutant decomposition purification system which performs a pollutant decomposition process. It is a plan sectional view which shows the pollutant decomposition purification system which concerns on other embodiment. It is a front sectional view which shows the main part of the pollutant decomposition purification system which concerns on other embodiment.

[First Embodiment]
The underground soil purification method according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 4.
The front sectional view of FIG. 1 shows a pollutant decomposition purification system 10 for performing the underground soil purification method of the present embodiment. In the underground soil purification method of the present embodiment, first, the impermeable wall installation step of installing the impermeable wall 22 is performed, then the pressurizing step of causing the board blistering in the ground 14 is performed, and then the flushing step is performed. Finally, the pollutant decomposition process is performed. Here, the pressurizing step of the present embodiment corresponds to the first step of the present invention, and the flushing step and the pollutant decomposition step of the present embodiment correspond to the second step of the present invention.

As shown in FIG. 1, the ground 14 targeted for purification by the pollutant decomposition purification system 10 is an alternating layer ground in which a water-permeable layer 16 and a water-impermeable layer 20 having a lower water permeability than the water-permeable layer 16 are alternately overlapped. ..
The ground 14 raised as an example in the present embodiment is formed on a water-permeable layer 16 (hereinafter, appropriately referred to as a water-permeable layer 16A) adjacent to the bottom of the water-impermeable layer 20 (hereinafter, appropriately referred to as a water-permeable layer 20A) closest to the ground surface. Contaminated soil 18 (net dot portion) containing pollutants is present. As examples of contaminants, organic compounds (for example, paints, printing inks, adhesives, cleaning agents, gasoline, xylene contained in thinners, etc., tetrachloroethylene, trichlorethylene, cis-1,2-dichloroethylene, chloro) Examples thereof include volatile organic compounds such as ethylene (that is, vinyl chloride monomer), benzene, etc.), heavy metal compounds, inorganic compounds, oils and the like.

The pollutant decomposition and purification system 10 includes an impermeable wall 22, an injection well 24, a pumping well 26, a pressure pump 27, a pumping pump 28, a water treatment device 30, and a regulating tank 32.

As shown in FIGS. 1 and 2, the impermeable wall 22 is provided in the ground 14 so as to surround the contaminated soil 18. As shown in FIG. 2, the impermeable wall 22 of the present embodiment has a rectangular shape in a plan view, but may have a shape other than the rectangular shape.

As shown in FIG. 1, the lower end of the impermeable wall 22 is embedded in the impermeable layer 20A adjacent below the impermeable layer 16A which is the target of decomposition and purification of pollutants. As a result, the contaminated soil 18 is surrounded and closed by the impermeable wall 22 and the upper and lower impermeable layers 20.

As shown in FIGS. 1 and 2, the injection well 24 and the pumping well 26 are provided at intervals so that the contaminated soil 18 is arranged in the ground 14 surrounded by the impermeable wall 22. Has been done. In the present embodiment, a pair of injection wells 24 are arranged on one side in the horizontal direction of the ground 14 surrounded by the impermeable wall 22 (the side in the arrow L direction in the drawing), and the other side in the horizontal direction of the ground 14 (in the drawing). A pair of pumping wells 26 are provided on the side in the direction of arrow R).

The pumping well 26, the pumping pump 28, the water treatment device 30, the adjusting tank 32, the pressurizing pump 27, and the injection well 24 are connected in this order via water pipes 34A, 34B, 34C, 34D, and 34E.

In the adjusting tank 32, a surfactant can be mixed with the treated water treated with water in the water treatment device 30 to generate a cleaning liquid 38. Further, the adjusting tank 32 can be heated to a temperature higher than the groundwater temperature at room temperature by a heater or the like provided in the adjusting tank 32, and then the heated cleaning liquid 38 can be sent out to the injection well 24. The cleaning liquid 38 may be heated to a temperature higher than the groundwater temperature at room temperature. As an example, the temperature of the cleaning liquid 38 is preferably 20 to 80 ° C, more preferably 25 to 60 ° C.

The cleaning liquid 38 may be any as long as it can desorb the contaminants in the contaminated soil 18 (underground soil) adhering to the soil particles of the contaminated soil 18 (underground soil) from the contaminated soil 18 (underground soil). .. As the surfactant that is mixed with the treated water to generate the cleaning liquid 38, an anionic (that is, anionic) surfactant, a nonionic surfactant having an HLB value of 7 to 18, and the like can be used.

Among these, the anionic surfactants include fatty acid salts, polyoxyalkylene alkyl ether acetates, alkyl sulfates, polyoxyalkylene alkyl ether sulfates, polyoxyalkylene alkylamide ether sulfates, monoglyceride sulfates, and olefin sulfonic acids. Salts, alkane sulfonates, acylated isethionates, acylated amino acids, alkyl phosphates, polyoxyalkylene alkyl ether phosphates and the like can be used.

Examples of the nonionic surfactant include polyoxyethylene alkyl ether, glycerin fatty acid ester, propylene glycol fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, tetraoleic acid polyoxyethylene sorbit, and polyoxyethylene polyoxypropylene. Glycol, polyoxyethylene polyoxypropylene alkyl ether, polyethylene glycol fatty acid ester, polyoxyethylene castor oil, polyglycerin fatty acid ester, alkyl glycoside and the like can be used.

Further, in order to generate the cleaning liquid 38, an effervescent agent, an admixture, an emulsifier or the like may be mixed with the treated water instead of the surfactant.

Of these, the effervescent agent is a hydrogen peroxide generating agent that dissociates into hydrogen peroxide and generates oxygen when dissolved in water (for example, hydrogen peroxide, persulfate, perborate, peracetate, alkali metal sulfate). Hydrogen peroxide adduct, alkaline earth sulfate metal salt hydrogen peroxide adduct, urea hydrogen peroxide adduct, melanin hydrogen peroxide adduct, amino acid hydrogen peroxide adduct, alkali metal peroxide or alkaline earth metal peroxide Etc.) and hydrogen peroxide can be used.

Further, as the admixture, methanol, ethanol, propanol, butanol, acetone or the like can be used.

Further, as the emulsifier, sodium stearoyl lactic acid, sucrose fatty acid ester or the like can be used.

It is not essential to mix these surfactants, effervescent agents, admixtures, emulsifiers, etc. with the treated water, and the cleaning liquid 38 may be hot water obtained by heating the treated water to a temperature higher than the groundwater temperature at room temperature. .. The cleaning liquid 38 is heated to a temperature higher than the groundwater temperature at room temperature to remove contaminants in the contaminated soil 18 (underground soil) adhering to the soil particles of the contaminated soil 18 (underground soil). It can be separated from 18 (underground soil).

In the water treatment apparatus 30, the pollutant is removed from the groundwater containing the cleaning liquid 38 in which the pollutant is dissolved and sent from the pumping well 26 by the pump 28 to perform water treatment.

In the flushing step, the cleaning liquid 38 generated in the adjusting tank 32 and heated to a temperature higher than the normal temperature of the groundwater is injected into the injection well 24, and the contaminants adhering to the soil particles of the contaminated soil 18 (groundwater). Is desorbed from the contaminated soil 18 (underground soil).

Then, the groundwater containing the cleaning liquid 38 in which the pollutants desorbed from the contaminated soil 18 (underground soil) is dissolved is pumped from the pumping well 26.

The contaminated soil 18 is in a state where the soil has been purified by the flushing step, but the contaminated soil 18 (underground soil) still contains pollutants. Therefore, a pollutant decomposition step is performed after the flushing step.

In the pollutant decomposition step, in the adjusting tank 32, the active agent is mixed with the treated water treated with water in the water treatment device 30 to generate the active liquid 42. The active liquid 42 can be heated to a temperature higher than the groundwater temperature at room temperature by a heater or the like provided in the adjusting tank 32. In the water treatment apparatus 30, pollutants are removed from the groundwater pumped from the pumping well 26 by the pumping pump 28 and sent in, and water treatment is performed.

The active liquid 42 may be any as long as it exists in the contaminated soil 18 (underground soil) and activates the decomposition activity of the decomposing microorganisms that decompose the pollutants. For example, as an activator that is mixed with treated water to generate an active liquid 42, a hydrogen sustained-release agent, an organic substance, a PH adjuster, a micronutrient, a trace element, or the like can be used.

Of these, organic substances include formic acid, acetic acid, propionic acid, butyric acid, lactic acid or citric acid or their sodium salts, potassium salts or calcium salts, glucose, fructose, galactose, lactose, maltose, trehalose, peptone, tripton, yeast extract. , Fuminic acid, vegetable oil and the like can be used.

As the PH adjuster, sodium hydrogen carbonate, sodium such as sodium carbonate, potassium carbonate, hydrogen carbonate, ammonium hydroxide, ammonium carbonate, sodium tripolyphosphate, disodium hydrogen phosphate, trisodium phosphate and the like can be used. Can be used.

Further, as the micronutrient, vitamin B12, vitamin B1, pantothenic acid, biotin, folic acid and the like can be used.

Further, as the trace element, Co, Zn, Fe, Mg, Ni, Mo, B and the like can be used.

The active liquid 42 is basically a formulation containing at least one of the above organic substances and micronutrients as an active agent, but other known purifying agents may be further added. At this time, the TOC concentration in the culture solution of the purifying agent is preferably 50 mg / L to 5000 mg / L, and more preferably 100 mg / L to 300 mg / L. However, it is not essential to set the TOC concentration to these values.

Further, the temperature of the active liquid 42 may be higher than that of groundwater at room temperature, and the temperature of the active liquid 42 is preferably 20 to 60 ° C, more preferably 20 to 35 ° C.

In the contaminated material decomposition step, the active liquid 42 generated in the adjusting tank 32 and heated to a temperature higher than the groundwater temperature at room temperature is injected into the injection well 24, and the active liquid 42 is sent into the underground soil 48 to send the contaminated soil 18 ( The degrading microorganisms present in the underground soil) are activated by the active liquid 42. Then, the decomposing microorganisms activated by the active liquid 42 decompose the pollutants desorbed from the contaminated soil 18 (underground soil).

(Action, effect)
Next, the process, action, and effect of the underground soil purification method according to the present embodiment will be described.
In the underground soil purification method according to the present embodiment, the impermeable wall 22 is installed in the impermeable wall installation step, and then the pressurizing step is performed.

(Pressurization process)
In the pressurizing step, water W is put into the adjusting tank 32 as an example, and the water W in the adjusting tank 32 is pressurized by the pressurizing pump 27 and injected into the injection well 24. Before injecting water W, the opening of the pumping well 26 is closed in advance.
When the water W of the adjusting tank 32 is pressurized by the pressurizing pump 27 and injected into the injection well 24, the permeable layer 16A is filled with the water W and the pressure of the permeable layer 16A containing the contaminated soil 18 increases. As shown, the pressure-injected water W pushes up the impermeable layer 20A above it to cause a blister, and forms a liquid passage (gap) S between the impermeable layer 16A and the impermeable layer 20A. do.

Since the permeation layer 16A is surrounded by the impermeable wall 22, the water W pressure-injected into the entire impermeable layer 16A surrounded by the impermeable wall 22 even when the water W is injected from a small number of places. Since the pressure of the above is applied, a liquid passage S through which the fluid can pass can be formed over the entire space between the water permeable layer 16A inside the impermeable wall 22 and the impermeable layer 20A on the upper side.

(Flushing process)
In the next flushing step, the pumping well 26 is opened, the cleaning liquid 38 is put into the adjusting tank 32 as shown in FIG. 4, the pressurizing pump 27 is driven to inject the cleaning liquid 38 into the injection well 24, and the pumping pump 28 is used. Is driven to pump water at the pumping well 26.
As a result, the cleaning liquid 38 passes through the liquid passage S between the water permeable layer 16A and the upper impermeable layer 20A, and the cleaning liquid 38 is distributed throughout the liquid passage S, and the cleaning liquid 38 injected into the liquid passage S is downward. As it penetrates toward, it flows toward the pumping well 26. That is, in the pressurizing step, the liquid passage S is formed in advance between the water permeable layer 16A and the upper impermeable layer 20A. Therefore, in the flushing step, the cleaning liquid 38 is passed through the liquid passage S to the water permeable layer 16A. The cleaning liquid 38 can be quickly spread over the entire upper surface, the cleaning liquid 38 can be rapidly permeated into the water permeable layer 16A below the liquid passage S, and the permeated cleaning liquid 38 can be flowed toward the pumping well 26.

By flowing the cleaning liquid 38 through the water permeable layer 16A in this way, the cleaning liquid 38 flows into the contaminated soil 18, and the contaminated material adhering to the soil particles of the contaminated soil 18 (underground soil) is removed from the contaminated soil 18 (underground soil). Can be detached from.
Then, the desorbed contaminated material is discharged from the contaminated soil 18 (underground soil) by pumping the groundwater containing the cleaning liquid 38 in which the contaminated material desorbed from the contaminated soil 18 (underground soil) is pumped from the pumping well 26. The contaminated soil 18 (underground soil) can be purified.

By heating the cleaning liquid 38 to a temperature higher than the groundwater temperature at room temperature, the solubility of the pollutants in the cleaning liquid 38 can be increased and the desorption of the pollutants from the contaminated soil 18 (groundwater) can be promoted.
As a result, the purification efficiency of the contaminated soil 18 (underground soil) can be improved.

Further, in the flushing step by the pollutant decomposition purification system 10 of the present embodiment, the viscosity of the cleaning liquid 38 can be reduced by heating the cleaning liquid 38, whereby the cleaning liquid 38 is made into a contaminated area (that is, the contaminated soil 18). ) Can be easily reached.

(Pollutant decomposition process)
After the flushing step is completed, the pollutant decomposition step is performed.
In the pollutant decomposition step, as shown in FIG. 5, the active liquid 42 is put into the adjusting tank 32, the active liquid 42 of the adjusting tank 32 is pressurized by the pressurizing pump 27 and injected into the injection well 24, and the pumping pump 28 Is driven to pump water at the pumping well 26.

In the contaminated material decomposition step, the contaminated material desorbed from the contaminated soil 18 (underground soil) by the flushing step is decomposed by the decomposing microorganisms activated by the active liquid 42 to purify the contaminated soil 18 (underground soil). can do.

Also in this contaminant decomposition step, the active liquid 42 passes through the liquid passage S between the permeable layer 16A and the upper impermeable layer 20A, and the active liquid 42 spreads throughout the liquid passage S, and the active liquid 42 is injected into the liquid passage S. Infiltrates downward and flows toward the pumping well 26. Therefore, the active liquid 42 is rapidly permeated into the permeable layer 16A below the liquid passage S, and the permeated active liquid 42 is used in the pumping well 26. Can be flushed towards.

By injecting the active liquid 42 heated to a temperature higher than the groundwater temperature at room temperature into the injection well 24, the degrading microorganisms are compared with the case where the active liquid 42 having a temperature equal to or lower than the groundwater temperature at room temperature is injected into the injection well 24. Can be more activated and promote the decomposition of pollutants. As a result, the purification efficiency of the contaminated soil 18 (underground soil) can be improved.

Further, in the pollutant decomposition step of the present embodiment, the viscosity of the active liquid 42 can be reduced by heating the active liquid 42, whereby the active liquid 42 is placed in the contaminated region (that is, the contaminated soil 18). It can easily reach a wide range.

In the underground soil purification method of the present embodiment, the purification efficiency of the contaminated soil 18 (underground soil) by the contaminated material decomposition step can be improved by performing the contaminated material decomposition step after the flushing step, and the contaminated soil can be improved. The purification period of 18 (underground soil) can be shortened.

Further, by performing the pollutant decomposition step after performing the flushing step to reduce the concentration of the pollutant, the inhibition of the action of the decomposing microorganisms due to the toxicity of the pollutant is less likely to occur. Therefore, it is possible to purify highly concentrated contaminated soil, which was difficult to purify soil by the conventional bio-purification method.

[Second Embodiment]
Next, the underground soil purification method according to the second embodiment of the present invention will be described.
The pollutant decomposition and purification method of the present embodiment includes a coarse-grained material filling step after the pressurizing step and before the flushing step.
In the coarse-grained material filling step, as shown in FIG. 7, the liquid passage S between the water-permeable layer 16A and the upper impermeable layer 20A is filled with the coarse-grained material 50 via the injection well 24. As the coarse-grained material, since it is necessary to allow water W to permeate through the liquid passage S, a granular material such as sand or fine gravel is used.

By filling the liquid passage S with the coarse-grained material 50 in this way, it is possible to prevent the liquid passage S from being crushed and disappearing due to the pressure from the upper side of the liquid passage S. Therefore, the shape of the liquid passage S formed in the pressurizing step can be reliably maintained even after the pressurization is stopped, and the cleaning liquid 38 is decomposed with respect to the permeable layer 16A in the flushing step. In the process, the active liquid 42 can be reliably flowed.

[Third Embodiment]
Next, the pollutant decomposition purification system 10 that performs the underground soil purification method according to the third embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.
As shown in FIG. 6, in the pollutant decomposition purification system 10 of the present embodiment, the injection well 24 is provided in the center of the ground 14 surrounded by the impermeable wall 22, and the pumping wells 26 are provided at the four corners of the ground 14. The cleaning liquid 38 and the active liquid 42 injected into the injection well 24 can be radially diffused by the permeable layer 16A and then pumped from the pumping wells 26 at the four corners.

[Other embodiments]
Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it is needless to say that the present invention can be carried out in various embodiments without departing from the gist of the present invention.

In the above embodiment, in the pressurizing step, water W is pressurized and injected into the permeable layer 16A to cause blistering, but a gas other than water W, for example, air or the like, is pressurized and injected into the permeable layer 16A. It can also cause board blisters.

The number and placement positions of the injection well 24 and the pumping well 26 in the above embodiment are examples, and the present invention is not limited to this, and the number and placement positions of the injection well 24 and the pumping well 26 are not limited to this. It can be changed as appropriate according to the range of the contaminated soil 18.

In the pollutant decomposition purification system 10 of the above embodiment, the impermeable wall 22 surrounding the contaminated soil 18 is provided on the ground 14, but the impermeable wall 22 may be provided as needed, and the impermeable wall 22 may be provided in some cases. It does not have to be provided.

In the above embodiment, an example of injecting the active liquid 42 heated to a temperature higher than the groundwater temperature at room temperature into the injection well 24 in the contaminated material decomposition step is shown, but the contaminated soil 18 (groundwater soil) is shown in the adjusting tank 32. ) May be mixed with the active liquid 42, and the active liquid 42 may be heated to a temperature higher than the groundwater temperature at room temperature to be injected into the injection well 24. That is, the decomposing microorganisms that decompose the pollutants contained in the contaminated soil 18 (underground soil) may be injected into the injection well 24 together with the active liquid 42.

In this way, the pollutants desorbed from the contaminated soil 18 (underground soil) by the flushing step are mixed with the active liquid 42 and decomposed by the degrading microorganisms activated by the active liquid 42, whereby the contaminated soil 18 is used. (Underground soil) can be purified.

Further, by injecting the decomposing microorganisms together with the active liquid 42 from the injection well 24, the number of the decomposing microorganisms in the contaminated soil 18 (underground soil) can be increased and the decomposition of the pollutant can be promoted. For example, in the flushing step, it is possible to supplement the decomposing microorganisms in the contaminated soil 18 (underground soil) reduced by the heat of the heated cleaning liquid 38.

In the above embodiment, in the pollutant decomposition step by the pollutant decomposition purification system 10, an example in which the active liquid 42 heated to a temperature higher than the groundwater temperature at room temperature is injected into the injection well 24 is shown, but in the adjusting tank 32, A purifying agent is mixed with the treated water treated by the water treatment device 30 to generate a purifying liquid, and the purifying liquid is heated to a temperature higher than the groundwater temperature at room temperature by a heater or the like provided in the adjusting tank 32. After that, the heated purification liquid may be sent out to the injection well 24.
That is, a purifying solution that is heated to a temperature higher than the groundwater temperature at room temperature and decomposes pollutants contained in the contaminated soil 18 (underground soil) may be injected into the injection well 24. The purifying liquid may be any as long as it can decompose the pollutants contained in the contaminated soil 18 (underground soil), and the purifying agent mixed with the treated water to generate the purifying liquid includes hydrogen peroxide solution, iron-based slurry and the like. Can be mentioned.

By doing so, the contaminated soil 18 (underground soil) can be purified by decomposing the pollutants desorbed from the contaminated soil 18 (underground soil) by the purifying liquid by the flushing step.

Further, by injecting the purifying liquid heated to a temperature higher than the groundwater temperature at room temperature into the injection well 24, the purification liquid in the purifying liquid is purified as compared with the case where the purifying liquid having a temperature lower than the groundwater temperature at room temperature is injected into the injection well. The reaction rate between the agent and the contaminant can be improved and the decomposition of the contaminant can be promoted.

Further, in the present embodiment, an example is shown in which a flushing step is performed after the pressurizing step and then a pollutant decomposition step is performed. However, if the contaminated soil 18 (underground soil) can be purified only by the flushing step. , The pollutant decomposition step does not have to be performed. Further, the pollutants to be purified in the flushing step and the pollutant decomposition step may be different.

10 Pollutant decomposition and purification system 16 Permeable layer
20 Impermeable layer 22 Impermeable wall 24 Injection well 26 Pumping well 38 Cleaning liquid (injection liquid)
42 Active liquid (injection liquid)
S liquid passage 50 Coarse grain material

Claims (3)

The permeable layer between the upper and lower permeable layers is pressurized to increase the internal pressure of the permeable layer to push up the permeable layer above the permeable layer to cause the board to bulge, and the permeable layer and the upper permeable layer are impregnated. The first step of forming a liquid passage between the layers and
After forming the liquid passage, a second step of injecting an injection liquid from one side of the water permeable layer and pumping the injection liquid from the other side of the water permeable layer to purify the water permeable layer.
How to purify the soil. The method for purifying soil according to claim 1, further comprising an impermeable wall installation step of installing an impermeable wall surrounding the permeation layer to be purified before the first step. The first or second aspect of the present invention, wherein in the second step, before injecting the injection liquid into the water permeable layer, the inside of the liquid passage is filled with a coarse-grained material so that the injection liquid can pass through. How to purify the soil.

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